Merge remote-tracking branch 'upstream/master'

Author: Vlad Stefan Munteanu

tox.ini

@@ -40,7 +40,7 @@ commands =
 
 [testenv:graphs]
 basepython=python2.7
-deps = graphviz==0.8
+deps = graphviz==0.8.1
 commands =
     python visualizer/visualize.py -i docs/source/_static